Neuropathic pain: Peripheral and central mechanisms

Neuropathic pain refers to a specific pain syndrome characterized by pain and sensory abnormalities in body parts that have lost their normal peripheral innervation or sensory representation. They are to be distinguished from other types of pain because of differences in the underlying pathophysiology and treatment. Following a peripheral nerve injury, a cascade of events occurs in primary afferents causing peripheral sensitization. Central sensitization, which is increased responsiveness in central neurons, is usually the result of an increased barrage from the periphery, but may also occur independent of such peripheral input. Again, a series of molecular changes contribute to this central sensitization. These peripheral and central sensitization phenomena in neuropathic pain represent the pathophysiological reason for the beneficial effect of antihyperalgesic treatment in this type of pain. In future, such treatment is likely to be replaced by agents that in a more specific ways attack the pain-generating mechanisms. (C) 2009 Published by Elsevier Ltd. on behalf of European Federation of International Association for the Study of Pain Chapters.